Is it possible to validate a schema defined date

Question

Hi,
Is it possible to validate a schema defined date in xsd as of a null type.
     <xs:element name="ContractDt">
<xs:restriction base="xs:date"/>
</xs:element>
In xml file if i want to keep date null and still should be valid......how do i do it
For eg: <ContractDt></ContractDt>
<ContractDt>1990-12-12</ContractDt>
Both the above should be valid.............and any other thing should be invalid. I know we can use patterns and ennumeration to achive this but...............all the other validations that come along schema defined datatype date are required........
Any help.
Regards,
Aru

Answer 1

Hi,
I meant this...........
<xs:element name="ContractDt" nillable="true">
          <xs:simpleType>
               <xs:union>
                    <xs:simpleType>
                         <xs:restriction base="xs:date"/>
                    </xs:simpleType>
                    <xs:simpleType>
                         <xs:restriction base="xs:string">
                              <xs:enumeration value=""/>
                         </xs:restriction>
                    </xs:simpleType>
               </xs:union>
          </xs:simpleType>
     </xs:element>
Hope my requirement is clear...
Aru